1. Technical Field of the Invention
The present application relates to a vehicle detection apparatus that detects vehicles during the hours of darkness, and to a vehicle detection program and a light control apparatus.
2. Related Art
Vehicle detection apparatuses have been known, which detect vehicles during the hours of darkness. A type of such a vehicle detection apparatus analyzes the absolute value of the brightness of a light source. Another type of such a vehicle detection apparatus analyzes the wavelength of the light emitted from a light source. Both of these types of vehicle detection apparatus can discriminate light originating from the headlights of a vehicle from light originating from an object other than vehicles. For example, such vehicle detection apparatuses are disclosed in Japanese Patent Application Laid-Open Publication Nos. 2005-092857 and 2005-534903.
However, in a vehicle detection apparatus utilizing the absolute value of the brightness of a light source, the brightness of the headlights of a vehicle may coincide with the brightness of light originating from an object other than vehicles. Thus, this type of detection apparatus has suffered from a problem that, if such coincidence occurs, a detection error may be caused, that is, light originating from an object other than vehicles may be determined as being originated from a vehicle.
Further, coincidence may also occur in a vehicle detection apparatus utilizing the wavelength of the light emitted from a light source, when it discriminates whether or not the light source is originated from a vehicle. Specifically, in such a vehicle detection apparatus, the wavelength of the reflection of the light emitted from the headlights of a vehicle may coincide with the wavelength of the light emitted from the headlights, per se. Thus, this type of vehicle detection apparatus has also suffered from a problem of causing a detection error at the occurrence of such coincidence.